The loss came despite much optimism before the kick off that Arsenal would set the benchmark for the title race this season.
But Wenger conceded that West Ham's early start to the season - having already played six Europa League qualifiers - came to opposite number Slaven Bilic's advantage.
"I felt we were a bit nervous and wanted to be too quick going forward in the first half. I don’t think we were too confident,” said Wenger.
“I think West Ham is a bit more advanced in preparation than us and have played many competitive games in the Europa League.
"I knew before the game that it would be a tricky game on that front and a big part was not to concede.”
Watch the full video of Wenger's post-match analysis here…
West Ham fitter than us - Wenger [AMBIENT]
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